Green roofs, roof gardens, eco-roofs all refer to the planting of vegetation on the roof surface of building structures. The principle of green roofs has been widely used in Europe for several decades. Roof top vegetation substantially reduces storm water run off, solar heat gain, and thermal transfer through the roof. In addition, large vegetated surfaces help to replenish oxygen through photosynthesis. Though the benefits are many, the typical green roofs costs are several times that of most roofing systems. The high price of typical green roof construction emanates from costly waterproofing procedures, extensive drainage layers, soil of depths ranging from eight inches to twenty four inches, and additional required structural construction to support resulting increased weight. Repairs to the roofing membrane are extremely expensive due to the large quantities of material that must be moved to access the waterproofing layer.
Each roofing manufacturer markets and sells roofing material of differing compositions, and each manufacturer offers warranties on its new roofing material. During construction of a roof, it is often desirable and/or necessary for the laborers to tread upon newly laid roofing. To minimize trauma to the newly laid roofing and to prevent the voiding of warranties on the newly laid roofing, each manufacturer markets and sells walk pad material that can be placed upon the newly laid roofing to allow laborers to walk atop the newly laid roofing with minimal damage and without voiding the roofing manufacturer's warranties. Each roofing manufacturer's walk pad is composed of material specifically engineered for use on that same manufacturer's roofing material. The use of any other walk pad or any other material on the roof risks damage to the roofing material and voiding of the manufacturer's warranty. This can present a major obstacle to the acceptability of green roof systems.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.